The association between the 2D:4D ratio and offspring sex at birth: A cross‐sectional study in Ghana

Abstract

The 2D:4D ratio is the putative marker of prenatal androgen exposure. Low maternal 2D:4D ratio has been associated with high or male-biased secondary sex ratio. Hitherto, there has not been any study in Ghana regarding the maternal 2D:4D ratio and sex ratio at birth. This study sought to investigate this observation in a Ghanaian population. The study was cross-sectional from December 2020 to April 2021 involving 272 first-time mothers. The mean ± SD age of the mothers was 23.9 ± 3.67 years. The right (2D:4DR), the left (2D:4DL), the mean (M2D:4D) digit ratios and the right-left difference (Dr-l) of the mothers were measured using computer-assisted analysis. The mothers were stratified by their digit ratios, and the cohort sex ratio (CSR) for each stratum was then calculated as the proportion of sons. The mean ± SD of the 2D:4DR of mothers-with-daughters and mothers-with-sons were 0.941 ± 0.032 and 0.933 ± 0.037, respectively. The mean ± SD of the 2D:4DL of mothers-with-daughters was 0.934 ± 0.034, while that of mothers-with-sons was 0.931 ± 0.039. The offspring sex at birth and the CSR was not associated with either the mother's right, left, mean 2D:4D ratio or their difference (Dr-l). However, mothers-with-daughters showed rightward asymmetry in their 2D:4D ratios as the Dr-l significantly and positively deviated from zero (p < .010). The maternal 2D:4D ratio may not be associated with their offspring sex at birth among first-time mothers. This study adds to the limited data on studies regarding offspring sex at birth and the 2D:4D ratio in Ghana and Sub-Saharan Africa.